In order to construct a safe flight plan, a pilot can make use of aeronautical charts showing relief; by applying overflight margins, the pilot can deduce waypoints and flight altitudes that can subsequently be input blind. This inputting can be performed using a dedicated terminal of the control and display unit (CDU) type. The safety of that technique is rather poor since it is associated both with the quality with which points and segments are input and with the quality of the use made of aeronautical charts.
Numerous anti-collision systems have been proposed for aircraft.
According to U.S. Pat. No. 6,421,603 B1, the pilot defines a route and the system verifies interference between the route and the ground on the basis of data contained in a “terrain” database. The pilot can modify the route in order to find a safe solution by successive iterations.
According to U.S. Pat. No. 6,424,889 B1 and French patent No. 2,789,771, a system calculates a horizontal trajectory for avoiding dangerous zones as a function of the relief known to a terrain database and as a function of constraints given by the pilot; that makes it possible to define a route that is deemed to be safe relative to obstacles, but it requires large computation resources. That system does not allow the pilot to control generation of the route; the pilot discovers the proposed solution once the calculation has terminated, and can then change the constraints in order to run a new calculation.
Those systems are not adapted to approach or takeoff stages, and they do not lead to an ergonomic display of the risks encountered during said stages of flight.
U.S. patent application Ser. No. 2003 107499 and French patent application FR 2 813 963 propose a device for providing assistance in air navigation for mounting on board an aircraft, the device including a display module arranged to display in real time a two-dimensional representation of the relief in front of the aircraft relative to the position and the movement of the aircraft; that representation relates to a region displayed in the form of an angular sector of apex corresponding to the position of the aircraft; according to those documents, the issuing of alerts is inhibited in part during a landing or takeoff stage.
Such a display system is not adapted to defining a safe approach or takeoff procedure for a rotary wing aircraft.
Document WO 02/39058 relates to a system for assisting air navigation by displaying navigation data in a horizontal mode and in a vertical mode on the appearance of an event such as detecting a nearby obstacle.
Such a system is not adapted to defining a safe approach or takeoff procedure for an arbitrary landing point.